Automatic reclosing circuit-breaker system



' Aug. 7, 1928. 1,680,129

} Hr W. BROWN AUTOMATIC RECLOSING CIRCUIT BREAKER SYSTEM Filed Dec. 171924 Inventvor: Haroid, w Brbwh;

His Atmorn Patented Aug. 7, 1928.

UNITED STATES PATENT orrica.

HAROLD w. BROWN,

or scnnnncrnma nnw YORK, Assmnoa TO GENERAL 'nrncrnrc COMPANY, Aconrormrron or new YORK.

Application filed December 17, 1924. Serial No. 756,607.

4 My invention relates to automatic reclosing circuit breaker systemsand particularly to such systems in-which a circuit breaker is arrangedautomatically'to connect a source 5 of current to a load circuit as soonas the load is such that the circuit breaker canv be reclosed withoutoverloading the source.

It is Well-known .to those skilled in the art that in systems in whichthe load circuit is arranged to be supplied with current at a pluralityof points, it isnecessary toa-rrange an automatic reclosing circuitbreaker system so that it will function properly under twodifferent'conditions of the load circuit. One of these conditions,called thestub end feed condition, is when all the'circuit breakersconnecting other sources to the load circuit are open, and the othercon-. dition, called the multiple feed condition, is when one or more ofthe other circuit breakers are closed so that the loadcircuit isenergized at substantially normal potential at some other point. r

One object of my invention is. topr'ovide an improved automaticreclosing circuit breaker system which will function'zproperly underboth of the above 'mentioned' con-- ditions of the load circuit. V Inaccordance with my invention I provide a single reclosing relay having ama netizing winding connected to a .suitab e source of current and anoperating winding connected so that the energization thereof varies inaccordance with the condition of the load circuit in response to whichit is desired to control the reclosing of the 'cir-' cuit breaker, andmeans for varying the conmotions of one of-the'windings of'said relay tochange the setting thereof so that it Will 40 operate properly tocontrol the closing of the circuit breaker under both of the abovementioned conditions. of the load circuit.

My invention willbe betterv understoo from the following descriptionwhen taken in connection with the accompanying drawing, which shows oneembodiment of my invention, and its scope will be pointed out in theappended claims.

Referring to the drawing, 1 represents a source of current, shown as adirect current generator, which is arranged to be connected to a loadcircuit 2 by means of a circuit breaker 3 which may be of any suitabletype. In order to simplify the drawing it is as- 'sumed that the groundis one side of load circuit. One terminal of the generator 1 is showndirectly connected to the ground and the circuit breaker 3 is arrangedto connect the other terminal to the metallic conductor of the loadcircdit. It is evident however that my invention is neither limited to agrounded system nor'to having the circuit breaker 3 controlthe'connection between only one terminal of the generator and thecorresponding side of the load circuit.

'As shown in the drawing, the circuit breaker 3 is of the well knownlatched-in type, having a closing coil 4,-which, when energized, closesthe circuit breaker, and an overload trip coil 5 which is connected to aresistance shunt 6 in the main circuit of the generator 1 and whichreleases the latch 7, that holds the circuit. breaker in its closed postion, when thecurrent supplied by the generator 1 exceeds apredetermined value. In order to control the reclosing of the circuitbreaker 3, in accordance with the load connected to the load circuitwhen the circuit breaker 3 is open, a resistor 8 of relatively highresistance is connected in shunt around the -main .terminals of the]circuit breaker. Therefore when the circuit breaker 3 opens,

the short circuit around the resistor 8 is opened and the currentsupplied by the sourceis reduced to a ve small value. The value of thissmall fee 'ng out current is dependent upon the toad-connected to theload circuit and also upon whether the load is beingdirectly suppliedatsome other point by some other source" such as generator 10 d. Erhichmay be connected to the load circuit means of a circuit breaker 11. Itis evident that under stub end feed condition, that is, when botli -ofthe circuit breakers 3 and-"'ll are open, the feeling out currentthrough the resistor' 8 produces a voltage,"

across. the load circuit which varies with the resistance of loadconnected to the load cirthe load circuit to effect the closing of thecircuit breaker. When, however, the circuit breaker 11 is closed and thecircuit breaker 3 is open, the voltage across the load-circuit for agiven load resistance is very much higher than when the load circuit isonly supplied through the current limiting resistor 8. Therefore anyreclosing relay which is adjusted to operate at the proper voltage underthe stub end feed condition operates to effect the reclosing of thecircuit breaker before the load has reduced to the proper value underthe multiple feed condition.

In order. to overcome this difficulty it has been the practice toprovide another reclosing relay which is arranged to control the closinof the circuit breaker in response to a di ferent value of voltage orsome other characteristic of the load circuit under .the multiple feedcondition, and have a selective relay arranged'to transfer the controlof the reclosing of the circuit breaker from one reclosing relay to theotherin accordance with the condition of the load circuit.

In accordance with my invention, I provide a single reclosing relay 19which is arranged to function properly under both of the above mentionedconditions of the load circuit. As shown in the drawing,

this relay 19 is of the directional type having an operating winding 20,a magnetizing windin 21 and a movable armature 22 fwhich is arranged tobe moved in opposite directions from a normal position in accordancewith the relative directions of the currents.v in the two windings ofthe relay. The relay 19 is constructed in any well known manner so thata predetermined voltage has to be impressed upon the operating winding,20 to move the armature 22 in one direction and a much higher voltagehas to be impressed ugmn the operating winding to move the armature inthe opposite direction. This result is obtained in the arrangementdiagrammatically shown in the drawing by opposing the movements of thearmature in t e respective directions by the centering springs 24 and 25which are adjusted for different values." In my copendmg application,Serial No. 482,630, filed July ,5, 1921, and assigned to the same assiee as this application, I have de scri d and claimed a preferred type ofrelay and also an arrangement for connecting the springs'24 and 25 tothe movable armature 22 so that the restraining forces in the twodirections are different and. may. be independently adjusted.

As shown in the drawing the o crating winding 20 is connected acrossthelbad cir-. cuit so that the relay operates in response to the voltageacross the vload c'ircuit. In

order that the setting of the relay may be zchanged in accordance withthe conditions of the load circuit, so that the voltage across the loadcircuit required to operate the re closing relay under the stub end feedcondition is lower than the voltage required under the multiple feedcondition, I provide an arrangement whereby the current flows throughthe ma netizing winding in one direction under t e stub end feedcondition and in the opposite direction under the multiple feedcondition. This reversal of current through the magnetizing winding sproduced by connecting the winding 21 as the center arm of a Wheatstonebridge which is formed by the four resistors 28, 29, 30 and that theratio of the resistance of the resistor 28 to the resistance of theresistor 29 is greater than the ratio of the resistance of the resistor30 to the resistance of the resistor 31. Therefore when the contacts 33of the relay 27 are open .some ofithe current that flows through theresistor 30 flows through the magnetizing winding 21 and the resistor29, whereas when the resistor 28 is short circuited by the contacts 33of the selective relay, the current flows through the magnetizing windinin the opposite direction. It is evident that if it were so desired, theresistor 28 could be made infinity, in which case only the'threeinfinite resistors 29, 30 and 31 would be required.

The windings 20 and 21 and restraining springs 24 and 25 are so arrangedthat when t e resistor 28 is short circuited'by the contacts 33, thedirection of circuit through the magnetizing winding is such that themovement of the armature 22 is opposed by the weaker s ringz. A

In ,or er to prevent the circuit breaker 3 from reclosing before theconditions on the load circuit have reached a stable condition after thecircuit breaker opens, a time relay 35 is provided which is arranged toprevent the-reclosin relay from operating until after the circuitbreaker has been open for a-certain length of time.

The 0 eration of the system shown is as follows: en the circuit breaker3 is. closed and'the load conditions are normal, the circuit breaker isheld in itsclosed 'osition .tain the armature in either of its circuitclosingJp'ositions.

pon the occurrence of an overload on theload circuit, the overload tripcoil 5 is sufficiently energized to release the latch 7 so that thecircuit reaker 3 opens. lVhen the circuit breaker opens, the shortcircuit-around the resistor 8 is removed so that the current sup lied bythe source 1 is reduced to a very smal value. This very small currentro-t iuces a voltage drop'across the resistor which is an indication ofthe load condition and by. means of the relay 27 is used to determinewhether or not another source is connected to the load circuit when thecircuit breaker I 3 is open.

"that the movement the magnetizing winding The closing of the auxiliarycontact 36 on the circuit breaker 3, when it'opens, connects the coil ofthe time relay 35 across the source 1. After a predetermined'timedetermined by the setting of the dashpot 38, the time relay 35 closesits contacts-37. and connects the Wheatstone bridge across the source 1.

If the load circuit is not supplied by some other source, the voltagedrop impresse upon the coil of the'relay 27 is sufficient to causetherela to operate and close its contacts33, there 28. Therefore whenthe time relay 35 closes its contacts 37, current flows through themagnetizing windin in such a direction,

o the armature 22 is. opposediby the weaker sprin which it will. beassumed is 25. Under these conditions,

the flux produced by winding 20 tends to.

move the armature 22 so that'the contact 40, carried by the armature 22engages the contact 41. As soon as the load resistance reaches apredetermined value, the voltage across the load circuit becomessuflicient to cause the armature to move from its middle position andconnect together the contacts 40 and 41. The closing of these contactscompletes a circuit for the closing coil 4 to close theci-rcuit breaker3. This circuit is from the ungrounded terminal of the source 1 throughthe contacts 37 of the time relay 35,. auxiliary contacts 44 on thecircuit breaker 3, contacts 40', and 41 of the 'reclosin'g relay 19,closing coil 4 to the ground. The open ing of the auxilia contacts 33 onthe circuit. breaker when it c oses, deenergizesthetime relay 35 which,in turn, disconnects the Wheatstone bridge from the source 1 sothatReclosing relay 19, therefore, 'is restored-to its normal'position. v

If the load circuit issupplied from some other source, such as thesource 10, after the -mined voltage, closed and the circuit oftheclosing coil 4 is completed to close the circuit breaker 3.

y short circuiting the resistor 21 sLde9nergized-.-

circuit breaker 3 o ens, the voltage impressed upon the-col of the relay27 is not suflicient to cause the relay to short circuit tlie resistor28. Therefore when the time relay 35 closes its contacts 37 to connectthe Wheatstone bridge across the source 1, the direction of currentthrough the magnetizing winding what it is under its stub end feedcondition. Therefore the operating winding 20 tends to move the armature22 in a direction to close the contacts 40 and 46. Since the movement ofthe armature in this direction is opposed by the stronger spring 24, therela 19 does not close its contacts 40 and 46 untihthe voltage acrosspredetermined value than is required under is in the opposite directionfrom the load circuit reaches a higher 7 the stub end feed conditions.When the load circuit voltage reaches this higher predeterthe contacts40 and 46 are This circuit is the same as the one above described-except it includes the contacts 40 and 46 instead of thecontacts 40 and 41.

While I have shownand described one particular arrangement forcontrolling the connections of a reclosing relay in accordance with theload conditions so as to change the setting thereof, it will be obviousto those (1 skilled in the art that various modifications I may be madetherein without departin from the spirit and scope of my invention. 1herefore, I do not desire tobe limited to'the exact arrangement shownand described, but seek to cover in the appended claims all "thosemodifications that fall within the true spirit and scope of myinvention.

What I claim as new and'desire to secure by Letters Patent of theUnitedv States, is:

1. In an' automatic reclosin'g' circuit breaker system, the combinationwith a source of current, a load circuit arranged to be supplied withcurrent'at a lurality of points, a circuit breaker arrange to connectsaid source to said load circuit, andclosing means for said circuitbreaker, of a polarized relay for controlling the operation of saidclosing. connected so that the energiz'ation thereof varies with theloadconnected to the load circuit when said circuit breaker is open, and

means whereby said relay controls the opera- .tionof said closing meansin response to diflt'erent conditionsof the load circuit comprlslngmeans operative 1n response. to a means having an operating windingpredetermined condition of said load circuit tovary '2. In breakersystem, the combination with, a

source of current, a load circuit arranged to be supplied with currentat a plurahty of; points, a circuit breaker arranged to connect saidsource to said load.ci rcu it, current limiting means arranged to beconnected the polarizationof said'relay. an automatic reclosing circuitin series with said source and said load cirsource of current, adistribution circuit arcuit when said circuit breaker is open, andranged to be supplied with current at a closing means for said circuitbreaker, of a plurality of points, a circuit controlling polarlzed relayfor controlling the operation device arranged to connect said source toof said closlng means having an operating said load circuit, means forefiectin the wlnding connected so as to be responsive to opening of saidcircuit controlling evice the. v tage across said load circuit, and uponthe occurrence of a predetermined abmeans operative in response to aprede normal load condition, current limiting termined condition of saidload circuit to means arranged be connected between vary thepolarlzation of sa1d relay to cause said source and sa1d load clrcultwhen sa1d sa1 relay to operate in response to a "diflfercircuit breakeris open, and closlng means cut volta e of the load circuit to effect thefor said circuit breaker, of a directional closingo said circuitbreaker. relay for controlling said closing means,

3. In an automatic reclosing circuit said relay having a movable memberarbreaker system, the combination with a ranged to be operated in twodifferent mansource of current, a load circuit arranged to ners to.efiect the operation of said closing be supplied with current at aplurality of means, restrainingmeans for opposing the points, a circuitbreaker arranged to connect movement of said movable member in each saidsource to said load circuit, current limitmanner, an operating windingfor said relay ing means arranged to be connected in series connectedacross said load circuit, a magwith said source and said load circuitwhen netizing winding for said relay c nec d said circuit, breaker isopen, and closing to said supply circuit, and means-operative means forsaid circuit breaker, of a relay when said circuit breaker'isopen andsaid for-controlling the operation of said closing load circuit issupplied with current at some means having an operating winding conotherpoint to change the connections of nected so as to be responsive to thevoltage sa1d magnetizing winding to said source across said load clrcuitand a magnetizing whereby: the flow of current through said a windingconnected to said source, and means operative when said circuit breakeris open and said load circuit is supplied with current at some otherpoint to chan e the connection of said magnetizing win ing whereby avoltage higher than the one required points, a circuit breaker arrangemagnetizing winding is changed.

6. In an automatic reclosing circuit breaker system, the combinationwith a source of current, a load circuit arranged to be supplied withcurrent at a lurality of g to connect when said load circuit is notsupplied at said source to said oad circuit, means for some other pointhas to be impressed across said operating winding to cause said relay toeffect the operation of said closing means.

4. In an automatic reclosing circuit breaker system, the combinationwith a source of current, a load circuit arranged to be suppliedwithgzurrent at a plurality of points, a circuit breaker-arrangedtoconnect said source to said load circuit, current limiting meansarranged to be connected in series with said source and said loadcircuit when said circuit breaker is open, and closing means for saidcircuit breaker, of a directional relay for controlling said closingmeans, said relay having a movable member arranged'to be moved in oposite directions from a given position to e ect the operation of sa1dclosing means, restraining means for opposing the movement of saidmovable member in .each direction, said restraining means beingadjustable to exert a greater opposing force in one direction than inthe a other, an operating winding for said relay connected across saidload circuit, a magnetizing winding for said relay,-and means operativein" response to a predetermined condition of said load circuit to changethe connections of one of said windings to reverse the direction of flowof currenttherein.

5. In an automatic reclosing circuit breaker system, the combinationwith a 'efiecting the openin of said circuit breaker upon the occurrenceof a predetermined abnormal load condi ion, current limiting meansarranged to be connected in series with said source and said loadcircuit when said circuit breaker is open, and closing means for saidcircuitbreaker, of a relay for controlling said closing means comprisinga movable armature, a magnetizing winding, a second winding connectedacross said load circuit and adapted to actuate said armature in onedirection or the other dependin upon the direction of flow of current trough said magnetizing winding, means opposing movement of said memberineither direction, said last mentioned means being arranged to exert. agreater opposition in one direction'than in the other, a lurality ofresistors connected to form a eatstone bridge connection, saidmagnetizing winding being connected across the central leg of the bridgeformed by said resistors, and means operative when said circuit breakeris open and said load circuit is supplied with current at some otherpoint to vary the resistance of one of the arms of the'Wheatstone bridgewhereby the direction-of current through said magnetizing winding isreversed. i W r 7. In van automatic reclosing circuit breaker systemwherein a circuit breaker is arranged to connect a source of current todirection forthe stub end feed condition a load circuit under stub endfeed and mulof said load circuit and in the opposite tiple feedconditions thereof, the combinadirectionfor the multiple feed conditionof 1 tion of a polarized relay for controlling the said load circuit.

reclosing of the circuit breaker in response In Witness whereof, I havehereunto set to the load condition of said load circuit, my hand this16%1A%% of December, 1924.

and means for polarizing said relay in one LD W. BROWN,

CERTIFICATE OF CORRECTION. Patent No. 1,680,129. Granted August 7, l928,to

HAROLD w. BROWN. It is hereby certified that error appears in theprinted specification of the above numbered patent requiring correctionas follows: Page 2, line [04, for the word "'infinite" read"finite'kpage 3, line 31, strike out the word ."drop"; and

that the said Letters Patent should be read with these correctionstherein that the same may conform to the record of the case in thePatent Office. Signed and sealed this 11th day of September, A. D. 1928.i:

v I M. J. Moore, (Seal) Acting Commissioner of Patents.

